Phosphorodithiolates

ABSTRACT

1. A PHOSPHORODITHIOLATE COMPOUND OF THE FORMULA:   R1-S-P(=O)(-S-R)-S-R2   WHEREIN R1 IS METHYL OR ETHYL, R2 IS CHLORINE OR BROMINE SUBSTITUTED ALLYL, AND R IS N-PROPYL.

Patented Oct. 29, 1974 United States Patent Ofice ABSTRACT OF THEDISCLOSURE Phosphorodithiolate compounds of the formula wherein R ismethyl or ethyl, R is allyl or halogensubstituted allyl and R isn-propyl or n-butyl, provided that R is n-propyl when R ishalogen-substituted allyl and R is n-butyl when R is allyl, which areuseful as nematocides controlling a wide variety of injurious nematodesand giving little phytotoxicity to plants.

The present invention relates to phosphorodithiolate compounds, andtheir preparation and use.

Conventional nematocides include D--D (a mixture of dichloropropene anddichloropropane), EDB (ethylenedibromide), DBCP(1,Z-dibromo-3-chloropropane), chloropicrin and the like. Thesenematocides diffuse through soil in the form of gas to kill nematodescoming into contact with the gas. However, covering or water-sealingtreatment for one or two weeks is usually necessary to com plete thenematocidal activity. By the terms covering and water-sealing are meantthat soil containing the gas is covered with a film such as plasticfilms and that the soil is filled with water through the gaptherebetween, respectively. Transplanting or sowing during which the gasremains in soil causes phytotoxicity, and therefore it is frequentlynecessary after such soil-treatment to leave the field as it is for along period or to carry out the socalled gas-removing treatmencomprising driving the gas out of the soil. Thus, sowing and setting areafter behind time, because the field must be left unplanted for a longperiod or because the tedious gas-removing treatment must be carriedout. That is, phytotoxicity disturbs remarkably an effective use of thefield. Moreover, chloropicrin causes the problems of pollution becauseof high toxicity thereof, and commercially available nematocidesmentioned above have a disadvantage that the cost per unit area isgenerally high.

As the result of the study of the pesticidal activity of variouscompounds, it has been found that a group of phosphorodithiolatecompounds of the formula:

wherein R is methyl or ethyl, R is allyl or halogen-substituted allyland R is n-propyl or n-butyl, provided that R is n-propyl when R ishalogen-substituted allyl and R is n-butyl when R is allyl exhibit astrong nematocidal activity against a wide variety of nematodesincluding soil nematodes such as cystnematode, root-knot nematode androot lesion nematode as well as rice white-tip nematode. It has alsobeen found that, in spite of their strong nematocidal activity, they donot show any material phytotoxicity even when applied while plants aregrowing Moreover, they are very less toxic to mammals. Thus, the saidphosphorodithiolate compounds [I] are excellent nematocidal agents witha high safety, which may be applied at any time.

The phosphorodithiolate compounds [I] can easily be prepared by treatinga phosphorodithioate compound of the formula:

Rl-O S wherein M represents an alkali metal and R and R are each asdefined above with a halide of the formula:

R -Hal [III] wherein Hal represents a halogen atom and R is as definedabove.

The phosphorodithiolate compounds [I] can also be prepared by treating aphosphorodithioate compound of the formula:

Rz-S 0 Rr-O S wherein R R and M are each as defined above with a halideof the formula:

R-Hal wherein R and Hal are each as defined above.

The phosphorodithioate compounds [II] and [IV] can be obtained by thereactions as shown in the following scheme:

S S O (RiO)1iE -SR MSH P RiSH wherein R, R R and M are each as definedabove. Specific examples of them are as follows:

As the halides [III] and [V], there may be exemplified1,3-dichloro-2-propene, 1,2-dichloro-2-propene, 1,2-dibromo-2-propene,1,3-dibromo-2-propene, l-chloro-Z-propene, 1-bromo-2-propene, etc.

The treatment may be effected in the absence or presence of an inertsolvent, usually at a temperature from room temperature to approximatelyC. or the boiling point of the inert solvent if used.

As the inert solvent, there may be preferably employed a solvent ofrelatively high polarity such as water, alcohols (e.g. methanol,ethanol) or ketones (e.g. acetone, methylethylketone).

The reaction time is associated with the other reaction conditions andmay be ordinarily from one to several hours.

In some cases, amines or iodides may be added to the reaction system foraccelerating the rate of reaction and increasing the yield.

3 The recovery of the phosphorodithiolate compounds [I] from thereaction mixture may be carried out by aper se conventional separationprocedure.

Some typical examples of the phosphorodithiolate compounds [I] are shownin Table 1.

TABLE 1 Compound Refractive number Chemicalstrueture index 1 n-CaH1S B!11 1.5468

I E"-SCH:4C J=CH:

2 n-C3H1S 0 n .1.5299

i -SCHzOH=CHCI (lzHsO 3 n-CaH1S 0 Cl n 1.5215

%S-CHr-C =CH:

4 n-CaH S O 71 1.5227

I E -SCH2( J=CHI 5 n-C;H1S 0 u 1.5325

1 S-OH:-CH=CHCI 6 n-C H1S 0 119 1.5482

'SCHz-(J=CHa 7 n-mms 0 an") 1.5120

S-CH2CH=OH2 CzHaO Some embodiments of the procedure for preparation ofthe phosphorodithiolate compounds [I] are shown in the followingExamples.

EXAMPLE 1 To a solution of 25.1 g. of potassiumO-ethyl-S-n-propylphoshorodithioate in 100 ml. of ethanol, 20.0 g. of1,2- dibromo-Z-propene are added, and the resultant mixture is stirredfor 2 hours under reflux. After removal of the ethanol from the reactionmixture by distillation under reduced pressure, a large amount ofbenzene is added to the residue. The resulting solution is washed with5% sodium carbonate solution and then wateraBy removal of the benzeneunder reduced pressure, there are obtained 28.8 g. ofO-ethyl-S-n-propyl-S-(2-bromo-2-propenyl)- phosphorodithiolate (CompoundNo. l) as a pale yellow oil of n 1.5409.

EXAMPLE 2 As in Example 1, 25.1 g. of potassiumO-ethyl-S-n-propylphosphorodithiolate, 11.1 g. of 1,2-dichloro-2-propeneand 100 ml. of ethanol are treatedvto give 22.4,g. ofO-ethyl-S-n-propyl-S-(Z-chloro 2 propenyl)-phosphorodithiolate (CompoundNo. 3) as a yellow oil of n EXAMPLES 4 TO 7 In the same manner as above,the following compoun are prepared:

0 Methyl S n propyl-S-(2-chloro-2-propenyl)- phosphorodithiolate(Compound No. 4), n 1.5227;

I 4 O Methyl S n pr0pyl-S-(3-chloro-2-propenyl) phosphorodithiolate(Compound No. 5), n 1.5325;

0 Methyl S n propyl-S-(2-bromo-2-propenyl)- phosphorodithiolate(Compound No. 6), n 1.5482;

0 Ethyl S n butyl-S-(Z-propenyl)-phosphorodithiolate (Compound No. 7), n15120.

As stated above, the phosphorodi-thiolate compounds [I] possess a strongnematocidal activity with less phytotoxicity' to plants. Some testresults, which ensure those facts, are shown below.

TEST 1 In a pot of ,4 are, 900 g. of soil contaminated with root-knotnematodes (Meloidgyne sp.) are placed, and a predetermined amount of ancmulsifiable concentrate containing the test compound (prepared as inExample I) is applied thereto. After mixing thoroughly, six tomato youngplants are transplanted (two replications). After three weeks, thegrowth and the degree of root-knot on which root-knot nematodes areparasitic as well as the phytotoxicity are observed.

The results are shown in Table 2 wherein the values of the plant heightand the root weight are the averages, and the degree of root-knot andthe phytotoxicity are classified into the following five grades:

Root-knot: i

Degree of root-knot..- 0 1 2 3 4 Degree of parasitism- None--- Low-Medium Higl1 Very high.

Phytotoxicity:

+ plant is almost dead.

TABLE 2 Growth Active in- Plant Root; Degree 0on1 und gredient heightweight of root- Phytonum er g./10a.) (0111.) (gJplant) knot toxicityStandard DBCP'. 3. 0 14. 6 0.51 0. 7 Standard D-D-. 1.5 No treatment 150 0 45 3 5 TEST 2 After application of the test compound as in Test 1,seeds of tomato are sowed, and the growth, the degree of root-knot andthe phytotoxicity are observed three No treatment In addition to thenematocidal activity, the phosphorodithiolate compounds [I] exhibitinsecticidal and acaridal activities. Since their acute and chronictoxicities to warm blooded-anirnals are low, they are practicallyutilizable as esticides articularl as nematocides. weeks thereafter. 5 Pp The results are shown in Table 3 wherein the criteria M of thephosphirodlthlolate compounds are areas in Testl liquid and can beapplied as such or together w1th any liquid or solid carrier, or in somecases, in a gaseous form.

Alternatively, they can be applied in conventional man- 10 ners asemulsifiable concentrates, wettable powders, oil TABLE 3 sprays, dusts,ointments, granules, fine granules, aerosols Growth or fumigantsformulated by any conventional method, if Active Plant Root Degreenecessary, including any auxiliary chemical. They can Compound gradientheight weight ofroot- Phytoalso be apphed, needless to say, in the formof mixtures nu r g-I 02.) m) -l kmt tmdcity with other nematocides,insecticides, herbicides, fungi- 1 0.38 11.2 0.17 0.2 cides, seeddisinfectants, fertilizers or soil disinfectants.

B1? 8:}? 3 I Some embodiments of the composition containing the 3.0 11.70.17 0 phosphorodithiolate compound [I] as an active ingredient 2 Q38 in18 0'1 are illustratively shown in the following Examples where- 0.7512.4 0.22 0 20 in parts are by weight.

1.5 12.4 0.24 0 3.0 12.3 0.16 0 EXAMPLE I 3 8 i3} 812 8 I hyl- -p py S0m 2-pr0p nyl)-ph0 1.5 10.1 0.09 0.1 :1: phorodithiolate (50 parts), anemulsifier (trade name Sorpol 3002) (20 parts) and xylene parts) are 4 ag. 0.: mixed thoroughly to make an emulsifiable concentrate.

is 1011 0114 0 I 3.0 10.1 0.12 0 EXAMPLE H 5 0 38 11 0 0 15O-Ethyl-S-n-propyl S (3 chloro-2-propenyl)-phos- 0175 1111 0116 '0 30phorodithiolate (25 parts), white carbon (13 parts), 3 :8 3: g laurylsulfate (5 parts), calcium ligninsulfonate (5 parts) 2 o 18 0 and clay(52 parts) are mixed and pulvenzed thoroughly 6 0.38 11.

1 2 1,1 3 g 3 to make a wettable powder. 310 1017 0: 10 0 EXAMPLE HI 70,1 0.2 O-Ethyl-S-n-propyl S (2 chloro-2-propenyl)-phos- 2 g-fi g Iphorodithiolate (5 parts) and clay (95 parts) are mixed 0 and pulverizedto make a dust. What is claimed is: $333353 ilg 40 1. Aphosphorodithiolate compound of the formula: Notreatment 9.4 0.08 3.5 s0 1 No germination. \l 2 TEST 3 wherein R is methyl or ethyl, R ischlorine or bromine substituted allyl, and R is n-propyl. vats of 40 cmX 30 there are transplanted 2. A phosphorodithiolate compound of theformula: kidney bean (2 leaves stage), cucumber (3 leaves stage), tomato(4 leaves stage), carrot (2 leaves stage), beet (4 114731315 0 leavesstage), tobacco (3 leaves stage) and lettuce (4 leaves stage). Sevendays after the transplantation, a pre- C H o 2 5 determmed concentrationof the test compound in solution is applied at a rate f 3 liters Per 2and the vats wherem R 1s chlorine or bromme-substituted allyl. are keptin a greenhouse. Phytotoxicity is observed 20 A Phosphorodlthlolatecompound of the formula! days after the application. Tests are carriedout in two l1-C3H7S o replications, i.e. a and b. CH=OHC1 The resultsare shown in Table 4 wherein the criteria 2 are as in Test 1. 02H) TABLE4 (iontcien- Kidney been Cucumber Tomato Carrot Beet Tobacco Lettuce 1';Compound number (p.513? a b a b a b a b a h a b a b 1..- 1,000 2' 1,0001,000 1,000 1,000 1,000 1,000 1,0oo----++:::-t+

7 8 4. A phosphorodithiolate compound of the formula: References Citedn-C3H1s 1 FOREIGN PATENTS P s-cH,o=oH, 29,847 12/1969 Japan 260-963 5 5.A phosphorodithiolate compound of the formula: LORRAINE WEIN] 3ERGERPflmary Exammer R. L. RAYMOND, Asslstant Examiner n-C H S 0 1' -s-omo=omUS. Cl. X.R. 9:350 10 260-979; 424-219

1. A PHOSPHORODITHIOLATE COMPOUND OF THE FORMULA: